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Google Tag Manager and Consent Mode v2

Redaktion ·

Google Tag Manager and Consent Mode v2

In 2026, Google Tag Manager (GTM) and Consent Mode v2 belong together inseparably: one manages your tracking, the other makes sure that tracking runs legally in the EEA. Anyone running Google ads in the European Economic Area can’t avoid Consent Mode v2 — it has been mandatory in practice since March 2024. This article explains both building blocks and how they mesh.

What Google Tag Manager is

GTM is a container you embed in your website once. After that you manage all tracking snippets — Google Analytics, conversion pixels, remarketing tags, third-party scripts — through a web interface, without touching the source code every time. How that works technically is covered in the glossary entry on Google Tag Manager.

Three terms form the framework:

  • Tags are the code snippets that do something — e.g. send a pageview to Analytics or report a conversion to Google Ads.
  • Triggers define when a tag fires — on pageview, on a click, on a form submission.
  • Variables supply the values tags and triggers need — such as a transaction total or a click URL.

The benefit: marketing can maintain tags without blocking development for every change. The container is versioned, tested, and published centrally.

Consent Mode is Google’s framework for coupling data collection to the user’s consent. Instead of hard-switching tags on or off, Consent Mode transmits signals that instruct Google’s tags to adapt their behavior to the consent given.

Consent Mode v2 works with four core signals:

  • ad_storage — enables storage (such as cookies) related to advertising.
  • analytics_storage — enables storage related to analytics, e.g. visit duration.
  • ad_user_data — sets consent for sending advertising-related user data to Google.
  • ad_personalization — sets consent for personalized advertising.

The last two signals (ad_user_data, ad_personalization) are the “v2” over the first version. They are precisely why the update became mandatory in the EEA.

There are two implementation variants that differ fundamentally — and the choice between them has both privacy and measurement consequences.

Basic Consent Mode: Google tags only load after the user has consented. If they decline, nothing fires — not a single ping is sent to Google. More privacy-friendly, but Google then has no data basis at all for the declining users.

Advanced Consent Mode: Tags load from the start. If the user declines, they send only an anonymous, cookieless ping without identifying information instead of full data. Google can model from these pings (see below). More measurement accuracy, but more delicate in privacy terms, because pings already flow before consent — a choice to be aligned with legal counsel.

How it works with the CMP

GTM doesn’t set the consent signals by itself — your Consent Management Platform (CMP), the cookie banner, does. The flow:

  1. The user makes their choice in the banner (consent or decline).
  2. The CMP translates that choice into the four Consent Mode signals.
  3. GTM reads the signals and controls whether and how the tags fire.

For this to run cleanly, the CMP should be Google-certified and ideally support the IAB TCF. A misconfigured banner is the most common reason Consent Mode doesn’t take effect despite a GTM setup.

Conversion modeling — estimating missing data

When a user declines, real conversion data is missing. In Advanced Mode, Google uses the cookieless pings to fill those gaps: from the observable behavior of consenting users and aggregated signals, Google models in the probable conversions of the declining users.

Industry estimates suggest 30 to 50 percent of conversions lost to declines can be recovered this way (as of 2026, estimated values, not a guaranteed figure). Modeled conversions aren’t exact single measurements but statistical projections — yet valuable for optimizing campaigns, because they reflect real performance more realistically than the consented conversions alone.

FAQ

Do I absolutely need Consent Mode v2? If you target users in the EEA or UK with Google ads: yes. Since 6 March 2024 it’s the prerequisite for continuing to use Google’s advertising and personalization data. Without valid signals, remarketing and personalized ads drop out for new EEA users.

What’s the difference between Basic and Advanced Mode? In Basic Mode, Google tags only load after consent — on a decline, nothing happens. In Advanced Mode they load immediately and send anonymous, cookieless pings on a decline, which Google models from. Advanced measures more accurately but is more privacy-sensitive.

Does GTM set the consent signals itself? No. The signals come from your cookie banner (CMP). GTM only reads them and then controls tag behavior. The CMP should be Google-certified.

What are the four consent signals? ad_storage (advertising cookies), analytics_storage (analytics cookies), ad_user_data (sending advertising user data to Google), and ad_personalization (personalized advertising). The last two are what distinguishes this from the first Consent Mode version.

How reliable are modeled conversions? They are statistical projections, not exact single measurements. Industry estimates cite 30 to 50 percent of conversions recovered. For campaign optimization they’re useful, but should be understood as estimates.

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